This invention relates to a building structure wherein heated air is supplied to spaces located in the walls, below the floor and above the ceiling of the building to provide a sheath of heated air surrounding the internal, useable space within the structure. The air supplied to these spaces is heated using low grade heat obtained from the ground, from either air or water obtained from below the hard frost line, from solar collectors, from biomass or from any other available source of such heat.
By definition, the term "low grade heat" as used herein denotes heat obtainable from various sources but at levels below the temperature needed for human comfort, i.e. below approximately 65.degree. F. The temperature below the hard frost line in northern regions of the United States remains substantially constant year round, at a low of approximately 45.degree. F. in northernmost states (except Alaska) to 50.degree.-55.degree. F. in the middle states. In southern regions which do not freeze, the ground temperature several feet below ground level remains constant year round at approximately 65.degree. F. The heat that is available from either air or water obtained from below ground at depths which do not vary in temperature year round is ideal as the source of low grade heat to be used in accordance with the principles of this invention.
U.S. Pat. No. 4,089,142, discloses a building structure including a concrete slab which forms the building structure foundation which supports the building enclosure mounted thereon and is interposed between the building enclosure and the ground. Means are provided for thermally insulating the periphery of the slab from the ground, downwardly from the surface of the ground to at least the extent of the ground frost line and the placement of a series of edge abutting parallel rows of end-to-end abutting hollow cinder or concrete blocks, in axial alignment underlying the concrete slab and axially aligned in heat transfer relationship therewith and with the ground below the frost line. The hollow blocks form a series of parallel transverse air circulation paths and means are provided for communicating these air flow paths within said blocks to the interior of said building enclosure such that thermal radiation entering the building structure interior and impinging upon the building interior causes heat to be circulated by air flow through said parallel air flow paths within the cinder blocks and within the interior of said building blocks acting as a heat sink.
The aforesaid patent discloses heating of the concrete slab by providing glass windows on the vertical walls of the building structure on the sides facing the sun to permit direct impingement of the sun on the upper surface of the concrete slab and building structure interior to thermally heat air flowing within the building structure by convection.
U.S. Pat. No. 3,527,921 discloses a building structure provided with a peripheral foundation insulated to approximately the depth of minimal seasonal temperature variations. The floor of the building is a concrete slab and sand is provided below the slab with electric heating mats located in the sand aproximately one foot below the slab to permit storing heat energy in the sand and in the ground beneath so that electric power can be used to heat the building for substantial periods of time either to take advantage of off-peak power or to minimize the effects of electrical power failures.
U.S. Pat. No. 3,965,694 discloses a system having the capability of being used as both a heating and cooling system. Therein, at least one heat pump is provided to pump heat from a heat source to the air conditioning system to prevent freezing of the system. The heat pump also removes heat from the system, when it is used as a cooling system, and diffuses it into the earth. The earth is also utilized as a source of heat to be supplied to the system.
None of the known prior art references provides or suggests the building structure of this invention, namely a building structure in which the useable living space is substantially surrounded by an insulating sheath of air, said air maintained at a temperature in the approximate range of 45.degree.-65.degree. F., said air being heated to this temperature range by a suitable source of low grade heat.